But that changed on Wednesday evening when Rosenstein announced that he had appointed another former FBI director, Robert Mueller, to conduct an independent investigation into Russia's interference in the 2016 campaign.
Zeidenberg was the assistant special counsel in the 2003 investigation into the leaking of the identity of Central Intelligence Agency officer Valerie Plame, which ultimately lead to Vice President Dick Cheney's advisor Scooter Libby being convicted of obstruction of justice, among other counts.
However, Republican representatives have grown increasingly anxious since Mr Trump sacked Mr Comey, who had been leading the bureau's probe - especially after Mr Comey's associates said he had notes from a meeting in which Mr Trump asked him to shut down the investigation into the Russian ties of his former national security adviser, Michael Flynn.
The President's adoption of the role of a victim has been a potent political weapon before and he has frequently used it to position himself against the Washington establishment, including the media which he uses as a foil in the absence of an easily identifiable political enemy, like Hillary Clinton. "We're talking more likely years than months". He may also release Mueller's findings publicly, given any legal or confidentiality restrictions.
"The problem with this whole process is the public doesn't find out what the heck is going on and whether our election was hacked", Zeidenberg said.
"I now have significantly greater confidence that the investigation will follow the facts wherever they lead".
Graham said he thinks "Congress' ability to conduct investigations of all things Russian Federation has been severely limited, probably in an appropriate fashion". These include "perjury, obstruction of justice, destruction of evidence and intimidation of witnesses".
"They're going to want to get tax records", Zeidenberg said.
Trump reiterated the claim hours later during a news conference with Colombian President Juan Manuel Santos. But Mueller's appointment apparently took some of the edge off.
Sen. Chris Murphy, D-Conn., also said Rosenstein had declined to provide details of the case, citing "the uniqueness of the investigation".